DMARC alignment
The domain match DMARC checks after SPF or DKIM passes.
DMARC does not only ask whether SPF or DKIM passed. It asks whether the passing domain aligns with the visible From domain. SPF alignment compares the Return-Path domain to the From domain. DKIM alignment compares the d= signing domain to the From domain.
reading this as developers picking email infrastructure
The question here is which one a backend engineer would rather operate. That means SDK depth in the language already in use, whether a retry can safely be replayed, how much the event log tells you when a customer says the email never arrived, and whether the pricing curve stays sane as volume grows.
Applied to dmarc alignment, that means weighing developer experience, SDK breadth, idempotency keys, and operating track record ahead of the rest, against password resets, receipts, and magic links shipped from application code.